The present invention generally relates to tire uniformity machines. The present invention more particularly relates to a grinding apparatus in a tire uniformity machine. Most particularly, the present invention relates to a linearly actuated grinding apparatus used for removing material from tires in a tire uniformity machine.
In tire uniformity machines, a tire is tested by rotating it at various speeds to ensure that the tire has been constructed and performs within quality standards. During this testing process, the tire is rotated and the tire uniformity machine examines the tire""s shape and surface characteristics to a high degree of accuracy. At times, during this examination, the tire uniformity machine detects irregularities in the tire. Any irregularity in the surface and shape of the tire may be corrected by removing material from appropriate portions of the tire.
To remove material, known tire uniformity machines typically employ a grinder having a single cylindrical grindstone rotating in relations to the rotation of the tire. As the tire rotates, the grindstone is selectively brought into contact with the tire to remove material.
In known grinders, the application of the grindstone occurs in a rotary fashion. The typical grinder has a pivoting arm on which the grindstone and its motor are mounted. Often a motor and gear box arrangement is used to control the speed and direction of rotation of the grindstone. The motor is then connected to the grindstone by belts or chains and a series of pulleys or sprockets. As will be appreciated, the motor and gear box are bulky and the positioning of this unit is limited. In fact, the typical motor housing projects to such an extent that the confines of the tire uniformity machine prevent the grindstone from being actuated in a linear fashion.
To overcome this, known tire uniformity machines attach the motor distally from the grinder on an arm that houses the drive belt or chain. In this way, the motor is located away from the instrumentation, the load wheel, and other devices that must be placed proximate to the test tire, where there is more space. The arm is mounted on a pivot such that the motor housing moves radially in a limited area. The pivot is located between the motor and grindstone, and the arm rotates under the force of a hydraulic cylinder attached to the arm on one side of the pivot. The typical hydraulic cylinder acts transversely of the arm and thus is mounted on a separate frame member than the frame member on which the arm pivots. So mounted, the hydraulic cylinders reduce visibility and access to the grinder and the area surrounding the grinder.
Due to the rotation of the arm, the grinder may not be aimed directly at the tire center. In other words, the center line and the contact point of the grinder travel in an arc in an attempt to tangentially contact the tire. As will be readily understood, initiating contact with the tire in this manner makes it difficult to make good, accurate contact in a repeatable manner. Further, the housing of the grinder must be adjusted to clear the machine housing and attempt to make proper contact between the grinder and the tire. Specifically, the grinder housing often is connected to a vacuum supply to remove particles created by the grinding process, and this housing must be made to closely fit the grindstone. Since this housing closely fits about the grindstone, in these devices, simple rotation of the arm may cause the housing to contact the rotating tire. As will be appreciated, such contact could significantly damage the grinding apparatus and may cause damage to the tire.
To avoid such contact and to better position the grindstone to remove material, known devices adjust the position of the housing and grindstone by rotating the housing relative to the arm. To make this adjustment, known devices incorporate a series of linkages. In some cases, as many as five linkages may be used. Due to machining tolerances, each link is a source of error. When multiple links are used, this error is compounded making it more significant in terms of accurate removal of the tire material. These errors make it difficult to achieve good contact with the tire.
In light of the current status of the art, it is an object of the present invention to provide a grinder that reduces the error associated with the use of multiple linkages.
It is a further object of the present invention to linearly actuate the grinder into contact with the tire.
In view of at least one of these objects, the present invention provides a grinder in a tire uniformity machine that receives a tire for testing, the grinder including an arm received in bearings; a grinding head supported on the arm, the grinding head having a rotatably grinding stone and a motor causing the rotation of the grinding stone; and a linear actuator operatively engaging the arm to selectively cause axial movement thereof causing the grindstone to selectively contact the tire.
The present invention further provides a grinder in a tire uniformity machine receiving a tire having a central axis for testing, the grinder including a support member; linear bearings mounted on the support members; an arm carried on the bearings and moveable toward or away from the tire; a grinding head supported on an end of the arm proximate the tire, the grinding head having a pair of rotatable grindstones adapted to contact the tire and at least one motor causing the rotation of the grindstones; and a linear actuator operatively engaging the arm causing the grindstone to move linearly to contact the tire.
The present invention further provides a method of removing material from a tire in a tire uniformity machine that rotates a tire for testing, the method including providing an arm; carrying a rotatable grindstone on an end of the arm; supporting the arm on linear bearings; driving the arm linearly toward the tire causing the grindstones to contact the tire; and rotating the grindstone as the grindstone contacts the tire.
The present invention further provides a grinding head in a grinder for a tire uniformity machine having a frame, the tire uniformity machine receiving a tire for testing within the frame, the grinding head including a grindstone rotatably supported in a shroud and directly driven by a motor mounted adjacent to the grindstone.
It accordingly becomes a principal object of this invention to provide a tire uniformity machine grinder of the character above-described with other objects thereof becoming more apparent upon a reading of the following brief specification considered and interpreted in view of the accompanying drawings.